Cooking Magnesium Rich Foods

Steamed spinach losing magnesium

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There is always the question of whether cooking causes the loss of magnesium in otherwise high magnesium foods. The answer would appear to be, “sometimes.” While many assume that there cannot be any loss as long as the cooking liquid is preserved and consumed (as with soup), and because magnesium is a mineral that cannot be broken downs so easily, there are some exceptions.

Michigan State University has conducted research that suggests the following:

The impact of cooking and processing on magnesium can vary greatly from food to food, since magnesium is found in different forms in different types of food. In some foods, where a greater percent of magnesium is found in water-soluble form, blanching (boiling or steaming for one to four minutes), steaming, or boiling of these foods can result in a substantial loss of magnesium. For example, about one third of the magnesium is lost in spinach after blanching. Similarly, when navy beans are cooked, they lose 65 percent of their magnesium.

In other foods that are rich in magnesium, like almonds or peanuts, there is very little loss of magnesium either from roasting or from processing into almond or peanut butter (as long as the whole almond or peanut is used).

Note that the above includes steaming. When the magnesium is in a water soluble form, it can disappear with the steam. Even with a lid on the pot, steam will escape, though at least some of it can be retained that way. Whether navy beans lose 65% of their magnesium when they are covered or not is something I could not find the answer to. Yet, it seems wise to assume there is some loss.

Spinach is more complicated. Raw spinach contains many phytates and oxalates. While phytates and oxalates are good for you in several ways, they also have the unfortunate effect of inhibiting magnesium absorption. Cooking spinach greatly reduces the phytates and oxalates, but it also reduces the other nutrients, and much magnesium is lost with the water or steam. The million dollar question is whether you lose more magnesium in the cooking than you would from the inhibiting effect of the phytates and oxalates. Such calculations make my head hurt, so I decide by choosing whether I prefer my spinach cooked or raw for each particular meal – and let nature sort it out. It never hurts to have a little variety in your diet.

None of this gives us any strong reason to cook or not cook our foods, but it is good to keep in mind. If you are trying to increase your magnesium levels, try to trap all the steam you can when cooking. If you can’t, just make up for it by eating more magnesium foods elsewhere.

"Please, no! My doctor tells me my magnesium levels are too low as it is!" - Image from



Magnesium Foods and Cardiovascular Health

Dietary Magnesium and Magnesum SupplementsA whole slew of news reports have recently covered two studies of the effects of dietary magnesium on cardiovascular health and strokes. It’s certainly good news, as it shows a clear connection between dietary magnesium intake and the two. The problem with the new reports, though, is that many of them simply say magnesium intake and leave the “dietary” part off. This is a big mistake.

People who read these reports may rush out and buy magnesium supplements to improve their cardiovascular performance. And that’s not a good idea, because there was nothing in the studies to connect magnesium supplements to cardiovascular improvement and reduce risk of stroke. The studies specifically looked at dietary magnesium, which means increased magnesium from eating magnesium rich foods.

Now the good news, if you are one of those who are ready to eat magnesium foods rather than popping pills.

In seven prospective studies, with 6477 cases of stroke and 241,378 participants researchers observed

…a modest but statistically significant inverse association between magnesium intake and risk of stroke. An intake increment of 100 mg Mg/d was associated with an 8% reduction in risk of total stroke (combined RR: 0.92; 95% CI: 0.88, 0.97), without heterogeneity among studies (P = 0.66, I2 = 0%). Magnesium intake was inversely associated with risk of ischemic stroke…

Again, this 100mg per day hasn’t been shown to work if you get it from a supplement. To get the effects noted in this study you need to get that 100mg of magnesium from food. It’s about 100 pumpkin seeds, 33 almonds, or a small serving of fish or spinach.

There are times when magnesium supplements have been shown to be effective, but this is not one of them. Be very careful when you use magnesium to treat a certain health issue, as in some cases the supplements to not have the efficacy of dietary magnesium. Don’t rely one blogs (not even this one) to give you this info. Look for the source of the study cited. Copy and paste it into Google, and read the abstract for yourself. It will take all of a minute or two. Make sure the study specifies either supplements or dietary magnesium. If it doesn’t, then it’s safer to assume that only dietary magnesium will work, as that’s often the case.

This particular abstract (Dietary magnesium intake and risk of stroke: a meta-analysis of prospective studies1,2,3,4, Susanna C Larsson, Nicola Orsini, and Alicja Wolk) can be found at the American Journal of Clinical Nutrition.

be found here.